planetarium

American  

[plan-i-tair-ee-uhm] / ˌplæn ɪˈtɛər i əm /

noun

planetariums, plural planetaria plural

1. an apparatus or model representing the planetary system.

2. a device that produces a representation of the heavens by the use of a number of moving projectors.

3. the building or room in which such a device is housed.

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planetarium British  

/ ˌplænɪˈtɛərɪəm /

noun

1. an instrument for simulating the apparent motions of the sun, moon, and planets against a background of stars by projecting images of these bodies onto the inside of a domed ceiling

2. a building in which such an instrument is housed

3. a model of the solar system, sometimes mechanized to show the relative motions of the planets

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Other Word Forms

Noun Inflected Forms

• planetaria
  plural
• planetariums
  plural

Etymology

Origin of planetarium

1765–75; < New Latin, noun use of neuter of Latin planētārius planetary; cf. -arium

Explanation

A planetarium is a theater where you can look at images of planets, stars, and other celestial bodies on the dome-shaped ceiling. Planetariums host school field trips by day, and can even host Pink Floyd laser light rock shows by night. Use the noun planetarium for the projector that shines light onto the surface of the building's dome, recreating solar systems and constellations — and also for the building itself, where such a show is put on. Because planetarium is a Modern Latin word (from the roots planeta, or "planet," and -arium, "a place for,"), its plural can be either planetariums or planetaria.

Example Sentences

See Examples For:

planetarium planetaria planetariums

A mobile planetarium allowing people to immerse themselves in the night sky has opened in Hull.

From BBC ● Apr. 3, 2026

That’s what happens when you have a payroll of $350 million and use it to amass more stars than the average planetarium.

From The Wall Street Journal ● Dec. 16, 2025

A 37-year-old convict, who had more than a year still to serve for theft, fled on November 14 during an outing with fellow prisoners to the city's planetarium.

From Barron's ● Nov. 28, 2025

Jessica Moon, from the observatory and planetarium describes Theresa as the "unsung hero" of the Armagh story.

From BBC ● Jul. 13, 2025

Instead, we take field trips to the planetarium and the Art Institute and the Field Museum.

From "South of Somewhere" by Kalena Miller

Eye of the Dream is an adaptation of this remarkable library of metadata, an audio-reactive Kaleidoscopic film for 360 domes and planetaria.

From The Verge ● Aug. 18, 2021

A feature of the Buhl star chamber with which Director Stokley is particularly Punch-pleased is an engineering stunt unique among the world's planetaria.

From Time Magazine Archive

There are now six Zeiss planetaria spotted across the country.*

From Time Magazine Archive

Thus, too, the four U. S. planetaria were made possible by gifts not from practicing esthetes but from a merchant, a soapmaker, a West Coast landowner, a socialite banker.

From Time Magazine Archive

Interest in planetaria is, I should say, an acquired taste; but there can be no doubt as to the industry and ingenuity of this inventor.

From A Wanderer in Holland by Marshall, Herbert, R. W .S.

An alternative kind of venue is offered by Cosm, which emerged after a merger involving Evans & Sutherland, a company that developed digital projection technology widely used in planetariums and science centres.

From BBC ● Mar. 30, 2026

Cosm — a name blending cosmos and colosseums — “is a nod to our history and heritage of great scientists and planetariums and engineers,” Terry says.

From Los Angeles Times ● Sep. 26, 2023

His creations, which ranged from tabletop size to more than 40 feet high, resembled a combination of planetariums, construction girders, carnival rides and pinball machines.

From Washington Post ● Jul. 31, 2021

Only groups or astronomical organizations, like clubs or planetariums, that register on a website to be set up this fall will be eligible for the fun.

From New York Times ● Aug. 4, 2014

As such they were comparable to the orreries of the 18th century and to modern planetariums; that they also showed the time and rang it on bells was almost incidental to their main function.

From On the Origin of Clockwork, Perpetual Motion Devices, and the Compass by Price, Derek J. de Solla (Derek John de Solla)